archive = zipfile.ZipFile(temp, 'w')
     for book in models.Book.tagged.with_all(shelf):
         if book.pdf_file:
             filename = book.pdf_file.path
     archive = zipfile.ZipFile(temp, 'w')
     for book in models.Book.tagged.with_all(shelf):
         if book.pdf_file:
             filename = book.pdf_file.path